The treatment of diabetes in humans, for the last sixty years, has relied on the daily injection of insulin recovered from the pancreatic tissue of cattle, pigs and occasionally sheep. More recently, human insulin, prepared either by chemical modification of porcine insulin or from fermentation of genetically-transformed E. coli cells has been used. In the last few years, transplantation of human pancreas has been attempted, but whilst the success rate has improved and a transplanted pancreas has remained operative for as long as two years, the process is still not considered reliable.
In U.S. Pat. No. 4,352,883 to Franklin Lim, there is described a method of encapsulating various cells, including Islets of Langerhans. This encapsulation procedure allows for the transplantation of the Islets into a mammal, with the Islets being able to react to circulating blood sugar levels and release insulin to control the disease, and yet not be subject to rejection phenomena. More recently, improvements have been made in the Lim process, as described in published European patent applications Nos. 0,127,713 and 0,127,989, assigned to the assignee hereof, such that microencapsulated Islets of Langerhans can survive and control blood sugar levels in a diabetic mammal for longer than one year. Such improvements have prepared the ground for experimentation with larger animals and, eventually, for clinical evaluation in humans as a treatment for diabetes.
Current procedures for the separation of Islets of Langerhans from an animal pancreas, for example, a calf pancreas, are carried out on a small scale by hand. The pancreas is cut into small pieces, the pancreatic tissue is contacted with collagenase in small tubes to digest some of the connective tissue and free the Islets, and the Islets are separated by centrifugation. This procedure requires repetitious treatments in order to separate the Islets cleanly from the pancreatic tissue debris. The operation is tedious since small volumes of materials only are being handled and often leads to death of many of the cells and a low overall yield of Islets.
The current Islet separation procedures are wholly inadequate to produce the volumes of Islets required for clinical evaluation of the microencapsulation process described in the above-mentioned patent and published applications. The present invention is directed to redressing this problem by providing method and apparatus for rapidly, effectively and essentially automatically processing pancreatic tissue to recover Islets.